Highly Differentiated Populations of the Freshwater Diatom Sellaphora capitata Suggest Limited Dispersal and Opportunities for Allopatric Speciation

Protist ◽  
2009 ◽  
Vol 160 (3) ◽  
pp. 386-396 ◽  
Author(s):  
Katharine M. Evans ◽  
Victor A. Chepurnov ◽  
Hans J. Sluiman ◽  
Sindu J. Thomas ◽  
Bryan M. Spears ◽  
...  
Keyword(s):  
Allopatric Speciation ◽  
Limited Dispersal ◽  
Freshwater Diatom

scholarly journals The role of allopatric speciation and ancient origins of Bathynellidae (Crustacea) in the Pilbara (Western Australia): two new genera from the De Grey River catchment

2019 ◽  
Vol 88 (4) ◽  
pp. 452-497
Author(s):  
Giulia Perina ◽  
Ana I. Camacho ◽  
Joel Huey ◽  
Pierre Horwitz ◽  
Annette Koenders
Keyword(s):  
Western Australia ◽  
Phylogenetic Relationships ◽  
Divergence Time ◽  
Molecular Data ◽  
Allopatric Speciation ◽  
New Genera ◽  
River Catchment ◽  
Divergence Time Estimates ◽  
The North ◽  
Limited Dispersal

The stygofaunal family of Bathynellidae, is an excellent group to study the processes that shape diversity and distribution, since they have unknown surface or marine relatives, high level of endemism, and limited dispersal abilities. Recent research on Bathynellidae in Western Australia (Pilbara) has uncovered new taxa with unexpected distributions and phylogenetic relationships, but the biogeographical processes that drive their diversification on the continent are still unclear. By exploring the diversity, distribution, and divergence time of Bathynellidae in a setting such as the perched and isolated aquifers of the Cleaverville Formation in the north of the De Grey River catchment (Pilbara), we aim to test the hypothesis that vicariance has shaped the distribution of this family, specifically if one or multiple vicariant events were involved. We analysed the specimens collected from perched water in different plateaus of the Cleaverville Formation, combining morphological and molecular data from mitochondrial and nuclear genes. We described two new species and genera (Anguillanella callawaensis gen. et sp. nov. and Muccanella cundalinensis gen. et sp. nov.), and two additional taxa are recognised using morphology and/or Automatic Barcode Gap Discovery and Poisson Tree Processes species delimitation methods. New genera and species result restricted to isolate perched aquifers on single plateaus and their distributions, phylogenetic relationships, and divergence time estimates support multiple vicariant events and ancient allopatric speciation.

Ultrastructure of Melosira resting cell rejuvenation

1984 ◽  
Vol 42 ◽  
pp. 734-735
Author(s):  
C. E. M. Bourne ◽  
L. Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Lake Michigan ◽  
Light And Electron Microscopy ◽  
Resting Cells ◽  
Planktonic Diatoms ◽  
Resting Cell ◽  
Vegetative Survival ◽  
Cytological Changes ◽  
Recent Attention ◽  
Freshwater Diatom

Much recent attention has been focused on vegetative survival forms of planktonic diatoms and other algae. There are several reports of extended vegetative survival of the freshwater diatom Melosira in lake sediments. In contrast to those diatoms which form a morphologically distinct resistant spore, Melosira is known to produce physiological resting cells that are indistinguishable in outward morphology from actively growing cells.We used both light and electron microscopy to document and elucidate the sequence of cytological changes during the transition from resting cells to actively growing cells in a population of Melosira granulata from Douglas Lake, Michigan sediments collected in mid-July of 1983.

Larval dispersal of Pocillopora damicornis at high latitude coral communities

2013 ◽  
Vol 1 (1) ◽  
pp. 3
Author(s):  
Hanny Tioho
Keyword(s):  
Larval Dispersal ◽  
Scleractinian Coral ◽  
Pocillopora Damicornis ◽  
Northern Limit ◽  
Significant Difference ◽  
Coral Communities ◽  
Limited Dispersal ◽  
Dispersal Distances ◽  
Latitudinal Range ◽  
Outer Area

In order to elucidate the patterns of dispersal in scleractinian coral Pocillopora damicornis near the northern limit of its latitudinal range, a total of 50 colonies (15-25 cm in diameter) of this coral were collected from Ooshima Island, Japan, and transplanted within one hour to the area of Satsuki, where they were not present before. Three concentric areas were established such as; the parental area (PA), intermediate area (IA) and outer area (OA). A total of 831 new corals were found in 1997 while 54.3% of these occurred in PA, 30.5% in IA and 15.1% in OA. In 1998, 52.3% of recruits settled in PA, 30.5% in IA and 17.2% in OA. A significant difference in the density of recruits was found among three areas, but recruit density was not significantly different between years and there was no interaction between area and year. There was no significant difference in the number of recruits among different directions, indicating no tendency for larvae to be concentrated in one particular direction. The present study suggests that the planulae of P. damicornis have limited dispersal distances at high-latitudes© Untuk menjelaskan pola penyebaran karang scleractinia Pocillopora damicornis yang berada di batas Utara penyebarannya, total 50 koloni (15-25 cm) dari karang ini dikumpulkan dari Pulau Ooshima, Jepang, dan di transplantasikan dalam waktu satu jam ke daerah Satsuki yang tidak ditemukan jenis ini. Tiga daerah ditetapkan yaitu, Daerah Induk (PA), Daerah Tengah (IA), dan Daerah Luar (OA). Sebanyak 831 karang baru ditemukan pada tahun 1997, sementara 54,3% ditemukan di PA, 30,5% di IA dan 15,1% di OA. Pada tahun 1998, 52,3% ditemukan di PA, 30,5% di IA, dan 17,2% di OA. Ditemukan perbedaan yang signifikan untuk kepadatan antara ketiga daerah tersebut, tetapi tidak ada perbedaan yang signifikan antar tahun dan tidak ada interaksi antara daerah dan tahun. Tidak ada perbedaan yang signifikan dalam jumlah pada arah yang berbeda sehingga hal ini menunjukkan tidak ada kecenderungan bagi larva untuk terkonsentrasi pada satu arah tertentu. Penelitian ini menunjukkan bahwa planula P.

scholarly journals Relicts from Glacial Times: The Ground Beetle Pterostichus adstrictus Eschscholtz, 1823 (Coleoptera: Carabidae) in the Austrian Alps

Insects ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 84
Author(s):  
Wolfgang Paill ◽  
Stephan Koblmüller ◽  
Thomas Friess ◽  
Barbara-Amina Gereben-Krenn ◽  
Christian Mairhuber ◽  
...  
Keyword(s):  
Ground Beetle ◽  
Distribution Patterns ◽  
Morphological Characters ◽  
Molecular Data ◽  
Ice Age ◽  
Dispersal Ability ◽  
Austrian Alps ◽  
Alpine Regions ◽  
Extant Species ◽  
Limited Dispersal

The last ice age considerably influenced distribution patterns of extant species of plants and animals, with some of them now inhabiting disjunct areas in the subarctic/arctic and alpine regions. This arctic-alpine distribution is characteristic for many cold-adapted species with a limited dispersal ability and can be found in many invertebrate taxa, including ground beetles. The ground beetle Pterostichus adstrictus Eschscholtz, 1823 of the subgenus Bothriopterus was previously known to have a holarctic-circumpolar distribution, in Europe reaching its southern borders in Wales and southern Scandinavia. Here, we report the first findings of this species from the Austrian Ötztal Alps, representing also the southernmost edge of its currently known distribution, confirmed by the comparison of morphological characters to other Bothriopterus species and DNA barcoding data. Molecular data revealed a separation of the Austrian and Finish specimens with limited to no gene flow at all. Furthermore, we present the first data on habitat preference and seasonality of P. adstrictus in the Austrian Alps.

scholarly journals Limited Dispersal, Deleterious Mutations and the Evolution of Sex

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 1053-1060
Author(s):  
Joel R Peck
Keyword(s):  
Mathematical Model ◽  
Sexual Reproduction ◽  
Genetic Locus ◽  
Genetic Material ◽  
Plant Population ◽  
Deleterious Mutations ◽  
Animal Populations ◽  
Offspring Sex ◽  
Limited Dispersal ◽  
Hermaphroditic Plant

Abstract This study presents a mathematical model that allows for some offspring to be dispersed at random, while others stay close to their mothers. A single genetic locus is assumed to control fertility, and this locus is subject to the occurrence of deleterious mutations. It is shown that, at equilibrium, the frequency of deleterious mutations in the population is inversely related to the rate of dispersal. This is because dispersal of offspring leads to enhanced competition among adults. The results also show that sexual reproduction can lead to a decrease in the equilibrium frequency of deleterious mutations. The reason for this relationship is that sex involves the dispersal of genetic material, and thus, like the dispersal of offspring, sex enhances competition among adults. The model is described using the example of a hermaphroditic plant population. However, the results should apply to animal populations as well.

scholarly journals Highly restricted dispersal in habitat-forming seaweed may impede natural recovery of disturbed populations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Florentine Riquet ◽  
Christiane-Arnilda De Kuyper ◽  
Cécile Fauvelot ◽  
Laura Airoldi ◽  
Serge Planes ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Spatial Scales ◽  
Mediterranean Ecosystems ◽  
Dispersal Distance ◽  
Genetic Connectivity ◽  
Restricted Gene Flow ◽  
Isolated Populations ◽  
Natural Recovery ◽  
Limited Dispersal ◽  
Ecological Importance

AbstractCystoseira sensu lato (Class Phaeophyceae, Order Fucales, Family Sargassaceae) forests play a central role in marine Mediterranean ecosystems. Over the last decades, Cystoseira s.l. suffered from a severe loss as a result of multiple anthropogenic stressors. In particular, Gongolaria barbata has faced multiple human-induced threats, and, despite its ecological importance in structuring rocky communities and hosting a large number of species, the natural recovery of G. barbata depleted populations is uncertain. Here, we used nine microsatellite loci specifically developed for G. barbata to assess the genetic diversity of this species and its genetic connectivity among fifteen sites located in the Ionian, the Adriatic and the Black Seas. In line with strong and significant heterozygosity deficiencies across loci, likely explained by Wahlund effect, high genetic structure was observed among the three seas (ENA corrected FST = 0.355, IC = [0.283, 0.440]), with an estimated dispersal distance per generation smaller than 600 m, both in the Adriatic and Black Sea. This strong genetic structure likely results from restricted gene flow driven by geographic distances and limited dispersal abilities, along with genetic drift within isolated populations. The presence of genetically disconnected populations at small spatial scales (< 10 km) has important implications for the identification of relevant conservation and management measures for G. barbata: each population should be considered as separated evolutionary units with dedicated conservation efforts.

Cyclotella deceusteriana, a new centric diatom species (Bacillariophyta) from the sub-Antarctic Region

Phytotaxa ◽  
2018 ◽  
Vol 333 (1) ◽  
pp. 108 ◽  
Author(s):  
BART VAN DE VIJVER ◽  
STEVEN DESSEIN
Keyword(s):  
New Species ◽  
Morphological Analysis ◽  
Central Area ◽  
Centric Diatom ◽  
New Taxon ◽  
Antarctic Region ◽  
Distribution And Ecology ◽  
Electron Microscopical ◽  
A New Species ◽  
Freshwater Diatom

During a survey of the freshwater diatom flora of the sub-Antarctic region (Iles Kerguelen and Iles Crozet) in the southern Indian Ocean, an unknown Cyclotella taxon was observed that was formerly identified as the presumed cosmopolitan C. meneghinana. Detailed morphological analysis based on light and scanning electron microscopical observations and comparison with several similar Cyclotella taxa worldwide justified the description of this unknown taxon as a new species: Cyclotella deceusteriana sp. nov. The new taxon is characterized by the presence of marginal fultoportulae on every costa, hyaline furrows between the raised marginal parts on which the striae are located, 2, occasionally 1, 3 or 4 central fultoportulae and an entirely flat, smooth, relatively small central area. The new species is described and compared with other Cyclotella taxa. Notes on its distribution and ecology are added.

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